fun
Explanation
The comic presents a single-panel scene showing an audience of adults and children at what appears to be a circus, all looking visibly horrified, disturbed, or uncomfortable at something happening off-panel. Below the image is text styled as a "Circus Fun Fact" that reads: "Clowns can retain basic motor function and survival instincts up to 18 months after decapitation as long as the brain stem remains intact."
The humor comes from the juxtaposition of a cheerful "fun fact" format with deeply disturbing content. The comic treats clowns as if they are a non-human species with bizarre biological properties (similar to how a chicken can briefly move after decapitation, but extended to a grotesque 18 months). The audience's horrified expressions confirm they are witnessing something awful, presumably a demonstration of this "fact." The joke works by combining the innocent, educational tone of a fun-fact caption with body horror, and by dehumanizing clowns into something biologically alien - a recurring comedy trope that plays on the common unease people feel around clowns (coulrophobia).